Existing communication and broadcast network infrastructures are divided into several sections. That is to say, the broadcast network infrastructures include ground wave based broadcast, CATV based broadcast, and satellite broadcast, and the communication network infrastructures include various types of communication networks, such as internet, mobile communication, and public switched telephone network (PSTN).
General subscribers are directly offered multi-channel broadcast through ground waves or offered through various medias, including a CATV cable broadcast network or a satellite broadcast network, using terminals, such as TVs, while being offered internet service and VOD (Video On Demand) broadcasting service through personal computers by ISP (Internet Service Provider).
However, since there are numerous types of broadcasting services using various media, a subscriber who wants to use various broadcasting services needs to own appropriate systems adapted to the respective broadcasting services.
That is to say, in order to offer CATV broadcasting service, a cable network and a system such as a set top box (STB) for CATV are required. In order to offer satellite broadcasting service, a separate satellite antenna and a satellite STB are required. In addition, in order to offer VOD service, an IPDSLAM system, a modem and separate equipment are required. In actual practice, however, the broadcasting services are not combined. Thus, a general subscriber for home use should pay huge costs in using a variety of services, resulting in extra financial burdens for being offered the services.
The existing network infrastructures, in which multimedia services are prevalently provided, cannot meet consumers' expectation for convergence service without separating the network into broadcast and communication infrastructures. However, there are increasing demands and expectations for integrated networks capable of implementing broadcast and communication convergence service.
Meanwhile, in public address systems installed in schools, businesses, buildings, etc., and capable of providing own announcement, there are increasing demands for constructing a broadcast communication convergence system, including a public address system.
However, since equipment used in a receiver end of the broadcast communication convergence system is simply constructed to perform only data relaying and processing functions, utilization efficiency of the equipment may be lowered.
In particular, when it is necessary to build a system capable of monitoring various pieces of environment information concerning, for example, necessity for ventilation due to carbon content in a classroom of a school, occurrence of a fire or a disaster, existence of students, an additional device should be installed separately from the receiver side equipment of the broadcast communication convergence system.
In addition, if power and information communication networks are destructed due to a disaster, it is not possible to present information about disaster areas and safety escape to many accident locations. In addition, a passive-type exit guidance lamp and emergency broadcast system, which indicates only predefined directions, simply indicates emergency exits and broadcasts only a fire alarm siren, irrespective of the accident locations, so that people may rush into stairways and hallways of the accident locations, resulting in catastrophic damage.